In a manner which is well known, oil is used in the field of motor vehicles for lubrication of, for example, the vehicle gearbox. For purification of the oil, an oil filter is normally used, through which the oil is caused to flow. During filtration, contaminants (for example in the form of solid particles) in the oil are separated from the liquid phase. The reason for this is that the oil is caused to pass through a porous layer in the oil filter, by means of which the contaminants remain in that layer.
For filtration of oil in the gearbox of a heavy goods vehicle, a so-called "spin-on-filter" is normally used, which is normally arranged on the outside of the gearbox and is connected to inlets and outlets for the oil that flows through the gearbox. The filter is constructed as a container, normally made of sheet metal, which contains an oil-filtering element in the form of a porous filtering material, through which the oil is fed. When the filter has been used for a period of time, it must be renewed, in which case the entire spin-on-filter is discarded and exchanged for a new filter. In this connection, the term "spin-on" refers to the fact that the filter-exchange is carried out by means of the filter being provided with a threaded portion, by means of which the filter can be screwed on directly during such an exchange.
Furthermore, in the case of trucks, there is in some cases also a need for cooling of the oil in the gearbox. In particular, such a need generally arises in countries having a warm climate, or in places where driving takes place in exceptionally exposed environments, for example in mines. According to known techniques, cooling of the oil is in this case carried out by means of an oil cooler being mounted between the gearbox pump and the oil filter. The oil that is utilized in the gearbox will thus be fed through the oil cooler, in which the oil is cooled down and is filtered in the oil filter. To this end, the oil cooler is provided with connections for an inlet and an outlet for a suitable refrigerant, for example water. In this case, the oil that is passing through the cooler can be cooled by the cooling water which is flushed through the cooler.
Although today's oil filters normally operate satisfactorily, they still have certain drawbacks. For example, the known type of spin-on-filter is not suitable to use due to environmental reasons, since the entire filter, including its casing, must be discarded when the filter must be renewed.
An additional drawback with this known technique is that the oil that is fed into the filter is relatively cold due to the fact that it has just passed through the cooler. Since cold oil is comparatively viscous, this provides for inferior flow through the oil filter. Furthermore, the oil that is fed through the oil cooler is contaminated, i.e. it is supplied directly from the gearbox and contains contaminants, for example in the form of particles. There is therefore a risk of these contaminants blocking the oil cooler, which can result in costly and undesirable breakdowns.
One of the objects of the present invention is thus to provide an improved device for cooling and filtration of a liquid medium, particularly oil, that is utilized in a motor vehicle, wherein the above-mentioned drawbacks are eliminated.